Liquid crystal light valves are an important element in a liquid crystal light valve projector. The liquid crystal light valve or LCLV receives light from a CRT on one side which activates a liquid crystal layer in the LCLV. On the other side of the LCLV a light source directs polarized light through the liquid crystal layer to a mirror behind the liquid crystal layer which in turn reflects the light back through the liquid crystal and out to the projection screen. If a segment of the liquid crystal layer is activated, then it changes the polarization of the light directed through the liquid crystal layer which causes that light to be projected onto the screen. If the liquid crystal layer is not activated then the polarization is not changed and that light will not be directed onto the screen.
The process for manufacturing the liquid crystal light valves involves a number of complicated steps for combining the various layers of the LCLV. The process starts with a BK-7 Glass substrate that has a 1,000 .ANG. layer of indium tin oxide (ITO) deposited on the BK-7 Glass substrate. The ITO is deposited on the substrate by evaporation which requires that the substrate be heated to a temperature of approximately 400.degree. C. before the ITO is deposited. It takes approximately 8 hours to achieve the thickness of 1,000 .ANG.. After the ITO is deposited, the substrates must cool down from the 400.degree. C. temperature before the next layer, which is the hydrogenated amorphous silicon layer ("a-Si:H"), can be deposited on the ITO. The a-Si:H is approximately 25.mu. thick. This thickness is necessary so that the a-Si:H layer will have the properties necessary to properly respond to the light energy directed at the a-Si:H layer. The amorphous silicon is then mechanically polished before the next layers are deposited on the amorphous silicon.
The process of evaporating the ITO onto the substrate consumes a significant amount of time and energy that adds cost to the process for making the LCLV. If a different process is used in which the ITO layer is sputtered onto the silicon dioxide at room temperature then the ITO deposit time can be reduced to approximately 20 minutes. However, when using ITO deposited by sputtering, the a-Si:H layer peels from the ITO layer during polishing of the a-Si:H film. Also, the ITO layer has a tendency to peel away from the BK-7 Glass substrate. The peeling of the ITO layer from the a-Si:H layer and the substrate causes a lower yield, cosmetic defects in the light valve and generally adds to the cost of the LCLV. Therefore, it would be desirable to use the sputtering process to deposit the ITO layer however, the peeling problem with the a-Si:H layer and with the substrate eliminates any processing efficiency gains made by using the sputtering process to deposit the ITO layer.